CHROYAMONTREY, Cambodia — In this village, and others like it throughout Cambodia, Muslims and non-Muslims live side by side in harmony, their existences unmarred by the toxic cocktail of government repression, separatist ambitions, and growing radicalism characteristic of many neighboring countries.

"I've been living with Muslim neighbors since I was young," says resident Ouk Ros. "When there's a marriage, we join together in the party."

Still, as money and influence from the Persian Gulf pours into Cambodia, many fear that pockets of the 400,000 strong Muslim community could fall into the orbit of a less-tolerant form of Islam.

"There are some organizations here from the Middle East that are very radical and that are very intolerant, and they are trying very hard to change the attitude and the atmosphere of the Muslim population here," the outgoing US Ambassador, Joseph Mussomeli warned in August.

A unique confluence of modern history, geography, and government initiative have combined to foster tolerance in Cambodia, many observers here say.

In Thailand and the Philippines, Muslim communities are concentrated in separate – and often disadvantaged – territories, which are byproducts of ancient kingdoms to which Muslims once belonged. Separatists in Thailand's south have been fighting for greater autonomy since 2004 and in the Mindanao area of the Philippines since the 1970s.

But Cambodia's Muslims, sometimes referred to as Chams – a reference to an ancient empire of warriors, the Kingdom of Champa – have always lived dispersed throughout the country.

"We don't have any separate lands, and we don't want any separate lands," says Osman Ysa, the author of two books on Cambodia's Cham population. "We consider this country as our own."

To date, Muslims here have also eschewed radical politics, although not without exception. In 2003, authorities arrested a Cambodian citizen, as well as an Egyptian and two Thai nationals, all suspected of ties to Jemaah Islamiyah, an Al-Qaeda affiliate based in South Asia.

Cambodia's unique and dark modern history helps explain why the dominant form of Islam remains both peaceful and accommodating, Muslim leaders say. When the ultra-Communist Khmer Rouge seized power in 1975, they outlawed religion and set about decimating the Muslim population. By 1979, when the Khmer Rouge fell, about 500,000 Muslims had been killed – nearly 70 percent – according to one of Mr. Ysa's studies.

As a result, the violence of Al Qaeda today reminds Muslim leaders of the Khmer Rouge of yesterday.

"We've already suffered a lot.... We are very disappointed by Al Qaeda because God tells: 'Don't kill people,' " adds Yousuf Bin Abetalip, an elder of Choy Changua, a village just outside of Phnom Penh, where about 300 Muslim families live.

Buddhism is the state religion in this country of 14 million, but the country's constitution enshrines freedom of worship. Unlike in China, where the Communist government has been accused of limiting the freedom of Muslims to worship, the government of Prime Minister Hun Sen has built large mosques and provided free radio airtime for Muslim programming.

Beyond such overtures, Muslims enjoy real political power. About a dozen serve in top political offices. Mr. Sen even has his own advisor on Muslim affairs.

But there are fears that Cambodia's moderate form of Islam could be contested. In recent months, ties between Cambodia and the Persian Gulf have grown as the Gulf States look to Cambodia as a potential buyer of oil and supplier of food. In September, the government of Kuwait pledged $546 million in soft loans, while Qatar pledged $200 million. Kuwait has also earmarked $5 million to refurbish a mosque in Phnom Penh.

There are fears that the money could open the door to private individuals and foundations who seek to influence the Muslim community here. Whether founded or not, in January, the Federal Bureau of Investigation (FBI) opened its first office in Cambodia, citing the potential for terrorism.

"Cambodia is an important country to us for the potential of persons transiting Cambodia – using Cambodia as a spot for utilizing terrorism," FBI director Robert Mueller said, inaugurating the new office.

In September, the prime minister announced a new law to more tightly control nongovernmental organizations. Sen's reasoning: "Terrorists might come to the Royal Government of Cambodia and hide themselves under the banners of nongovernment organizations."

Some critics contend the law is not aimed at terrorists, but nongovernmental organizations (NGOs) that routinely criticize Sen's administration.

"It's not only to control the terrorists groups, but also to control NGOs in general," says Thun Saray, the director of Adhoc, a human rights organization based in Phnom Penh.

As concern over terrorism grows, Muslims here, including Mr. Abetalip, say they will be the first to prevent it. "If there's any Cambodian people who want to follow Al Qaeda, we will straight away arrest them and bring them to the government."